1. Field of the Invention
The present invention relates to idle control in an internal combustion engine, and particularly the control of the air supply to the engine during engine idling.
2. Related Art
In order to improve engine torque at high engine speeds, automotive internal combustion engines have been developed which have a larger air intake manifold volume for a given engine displacement. At the same time, engine accessories and other ancillary consumer units in motor vehicles are constantly being improved and in some cases converted from being mechanically driven to being electrically driven. This has the effect of lowering the idle load placed on the engine, and hence the minimum desirable engine speed.
It therefore becomes more important that an engine should respond quickly to any sudden increase in engine load at idle speeds, for example owing to a sudden increase in alternator demand or power steering demand, in order to avoid stalling of the engine. However, a large intake manifold volume to engine displacement ratio and a lower idling speed both reduce the speed of response to changes in inlet airflow.